Circuit breaker



1941. J. H. BURNSIDE, 2,0

CIRCUIT BREAKER Filed June 11, 1940 7 Sheets-Sheet l INIVENTOR.

' IIHIIIIIIII James H. Bum/1 side 2 fl w N 19 1. J. H; BUR'NSIDE; 2D 2,261 139 CIRCUIT BREAKER Filed June 11, 1940 7 Sheets-Sheet 2 INVENTOR. James l-Burnside 22 Maw Nov. 4, 1941. .1. H. BURNSIDE, 20 2,261,139

CIRCUIT BREAKER Filed June ll, 1940 7 Sheets-Sheet s INVENTOR. Jhmea H Burnside 2'11- 1941- J. H. BURNSIDE, an I 2,261,139

CIRCUIT BREAKER Filed June 11, 1940 7 Shee'bS Sheet 4 INVENTOR. Jame-S l fawrns 'de 252 so 89 IIIIIIII 95 4, 1941- J. H. BURNSIDE, 2D 2,261,139

CIRCUIT BREAKER 7 Sheets-Sheet 6 1N VENT OR. @Emes h. Burnside 2 MM r , construction which minimizeswear on the parts 5 Patented Nov. 4, 1941 h CIRCUIT BREAKER James H. Burnside, 2nd, New York, N. Y., assignor to Circuit Breakers Corporation, New N. Y., a corporation of New York York,

Application June 11, 1940, Serial No. 3393M 16 Claims.

This invention relates to improvements in circuit interrupting devices of the type including overload actuating mechanism of one form or another for causing the switch to open the circuit when a predetermined load is exceeded.

More particularly, the invention is concerned with circuit breakers which are small,si-mple structurally, and inexpensive to manufacture so as to be competitive with ordinary fuses as emplayed in house lighting circuits and the like.

The general, most important, object of the invention is, therefore, to provide in a compact, rugged and inexpensive form a circut breaker which may be employed in the place of ordinary fuses in house lighting circuits,

A further object of the invention is the provision of a switch of this type so constructed and arranged so as to be manually closable and yet not capable of being held closed when overload conditions exist in the circuit to which it is connected.

A further object of the invention is the provision of a small circuit breaker of this type which will meet the requirements to which devices of this type are subjected before being approvedfor use, including the breaking of overloaded circuits without suilicient flaming to cause fires or injury.

A more specific object of this invention is to provide circuit breakers of this type of both single and double pole forms mounted in special casings therefor or in a casing similarly shaped and little larger than the usual screw plug type of fuse.

A still further object of the invention is the provision of a circut breaker in which the cooperating fixed and movable contacts interengage to lock the switch in closed position.

Another object is to provide in a switch of the above type mechanism for automatically destroying the locking engagement between the contacts upon overload.

'A still further object of the invention is the provision in circuit breakers of the above type of a structure by means of which the movable member on which the movable contact is mounted is capable of movement under the stresses placed thereupon by reason of the locking interengage ment of the contacts to ensure proper alignment of the contacts and hence a low contact resistance therebetween.

A more specific object of the invention is the provision in a circuit breaker of this type of a most subject thereto in order to ensure the ability contact carrier in elevation to operate many hundreds of times without wearing out. o

A still more specific object of the invention is the provision of a circuit breaker of this type having a bimetal overload release in which the bimetal element is so constructed as to cause a minimum current loss in the device itself when in continuous use.

Another specific object or the invention is the provision of a construction which minimizes the tendency of the adjacent portions of the housing to carbonize and become a high resistance conductor.

Many other and more detailed objects of the invention will be apparent from the following detailed description when taken in connection with the attached drawings.

This invention resides substantially in the combination, construction, arrangement and relative location of parts, all in accordance with this disclosure.

In the accompanying drawings, Figures 1 to 19, illustrate the single pole form of device with special housing, wherein 25 Figure l is a top plan view thereof; Figure 2 is a right hand side elevational view thereof;

Figure 3 is a view taken on the line 3--3 of Figure 2, that is, with thecover of the housing removed;

Figure 4 is a bottom plan view of the switch housing as it appears when removed from its supporting base;

Figure 5 is a bottom the housing;

Figure 6 is a cross-sectional view taken on the line 6-6 of Figure 1, omitting some details in order to illustrate the explosion chamber;

Figure 7 is a similar view taken on the line |--'I of Figure lshowing a portion of the movable the plan view of the cover for Figure 8 is a cross-sectional view taken on line 8-8 of Figure 1;

Figure 9 is a cross-sectional view taken on removed, showing the switch in open circuit position Figure 11 is a similar view showing the carrier moved toits extreme clockwise position;

Figure 12 is a view taken on the line l2'l2 of Figure 8 showing certain parts in cross-section and leaving the parts mounted on the lower side of the main cover in place; these parts being in open circuit position;

Figure 13 is a view similar to Figure 12 but showing the parts in a position corresponding to that of Figure 11;

Figures 14 and 15 are views similar to Figures and 11; Figure 14 showing the parts in position just before the main contacts close and Figure 15 showing the final position of the parts when the contacts are closed;

Figures 16 and 17 are views similar to Figures 12 and 13 with the cover parts in positions corresponding to the position of the other parts as illustrated in Figures 14 and 15, respectively;

Figure 18 is a view taken along the line I8-l8 of Figure 9;

Figure 19 is an enlarged detailed view of the bimetal element and its support;

Figure 20 is a perspective view of the doublepole form of switch;

Figure 21 is a front elevational view thereof with the top cover removed, that is, on the line 21-41 of Figure 20, showing the operating shaft in cross-section;

Figure 22 is a plan view similar to Figure 21 with the cover of the oscillatable contact carrier removed, showing the switch in "01? position or open circuit position; I

Figure 23 is a bottom plan view of the housing with on part broken away:

Figure 24 is a considerably enlarged view sim ilar toFigure 22 with some parts broken away, showing the switch in on" or closed position;

Figure 25 is a top plan view looking into the main housing with the oscillatable contact carrier removed, showing some parts in cross-section;

Figure 26 is a cross-sectional view taken on the line 26-26 of Figure 22;

Figure 27 is a top plan view of another form oi. single-pole switch with a circular housing shown in full size;

Figure 28 is a side elevational view thereof;

Figure 29 is a bottom plan view thereof;

Figure 30 is a top plan view with the housing cover removed; and

Figure 31 is a cross-sectional view taken on the line 3I-3I of Figure 30.

Reference-is made to the fact that the various structures herein disclosed are in some respects similar to the subject matter disclosed in my copending application Serial No. 185,145, filed January 15, 1938, for Circuit breaker, and my issued Patents Nos. 2,l62,935 and 2,204,528.

A great deal or effort, time and money has been spent in an attempt to build a circuit breaker which would be comparable in size to the ordinary screw type or fuse plug now commonly employed for the protection of electric light and power circuits. The tests to which such devices are put by the Fire Underwriters Laboratories before they are approved for use are so severe that while circuit breakers have been developed and are sold for this purpose they are relatively large and expensive, with the result that a truly competitive switch for these uses has not yet been produced. The switch herein disclosed is little larger than a screw type of ruse plug, and in accordance with this invention has been so simplified in structure as to be competitive therewith in cost. The devices of the figures of these drawings are substantially iullsizeanditwillbeseenthatthescrewplug type of circuit breaker illustrated in the drawmechanism of the various forms of the inveii tion has been so simplified and constructed as to be capable of meeting all the tests for approval and is entirely capable of withstanding many hundreds of repeated operations.

The details of construction and the purposes thereof will best be understood by describing the various devices as a result 01 which the objects of the invention will become more apparent. The structure of Figures 1 to 19, inclusive, -will first be described. 7

As illustrated in the various figures, it includes a base I of suitable insulating material which, as is clear from the drawings, consists of a substantially rectangular body of insulating material cut away intermediate its ends and throughout its width as indicated at 2 to receive the main housing 3 which is likewise oi a suitable insulating material. This housing is of substantially rectangular form and is provided with a removable cover 4 held on the housing by means of the screws 5. The housing is held in the base by means of the screws 6. At diametrically opposite corners the base is provided with holes I through which screws orbolts may be passed for mounting the switch. At one end of the base is a terminal strip 8 provided with a binding screw 9 by means of which one of the circuit wires may be attached and at the other end is a terminal strip Ill provided with a binding screw I I by means of which the other circuit wire may be attached. It may be here noted that the structure now being described is of the single pole type.

The removable cover 4 is provided with a short shaft I2, one end of which is secured in any suitable way as by molding in a manual operating knob I3, as illustrated for example in Figure 8. The other end of the shaft, which has fiattened sides, as illustrated clearly in Figure 8, has mounted thereon a cam 35 which has a complementary' opening so that the shaft and cam must move together. The cam is held on the shaft by means of a screw 34 having a cylindrical head as shown in Figure 8. Thus when the manual operating knob I3 is rotated cam 35 rotates with it close to the under-surface of the cover 4. Formed on top of the cover 4 at a suitable point is a stop I4 which engages one end of the knob I3. In the other end of the knob is a spring pressed detent comprising a ball I5 and a spring I6, see Figure 2. As shown in Figure I the cover is provided with a depression IT in which the ball I5 rests when the switch is in "on position, at which time it is straight up and down.

The conductor strip I 0 extends up into the housing from the bottom, see Figure 8, and has secured thereto in conducting relation the main fixed contact I8. That portion of the housing adjacent this contact is shielded by means of a piece of insulating material I 9 of suitable characteristics, such as horn fibre, which does not carbonize in the spark resulting when the circuit breaks. Thus the high resistance of the switch is maintained througha long life.

As is clear from Figure 18, the housing I is shaped to form a chamber on the interior thereof which for a considerable portion thereol' is substantially circular. Mounted in this chamher is the movable contact carrier or member II which ismade of any suitable insulating material, preterably in the form of a cylinder. This member is hollow and contains the operating ings is about the size or a screw plug !use. The mechanism of the switchi It is provided with a removable cover 2| which is held thereon by means of a screw 22. The sides of the carrier 20 and the cover 2| are of complementary shape and interengage so that there is no tendency of one to rotate with respect to the other. On top of the cover 2| is pivotally mounted on the pivot pin 23 a latch 24 which is engaged by a spring 26, as illustrated clearly in Figure 3. The lower end of the latch 24 engages, as will be described later, in a notch 25 in the circular wall of the main housing. A finger 21 extends up through the cover 20 through a suitable opening therein and by means of it, as will be explained later, the switch may be manually opened through,the operating knob I3 when desired. The cover 2| has an upwardly extending shoulder 28 formed thereon for cooperation with the cam 35, as will be explained later.

Extending downwardly through the wall of the main housing in the region of the fixed contact I8 is a passage 29, see Figure 6, which opens into a chamber 30 formed by a recess in the bottom or the housing d, which is closed by the base i when the parts are assembled. The base i is provided with an aperture 36 which connects this chamber with the atmosphere.

In the bottom wall of the main casing 3 is a recess in which a spiral spring 3| lies. The inner end of this spring engages in a slot in the lower end of a lead strip 43 (Figure 4) which extends upwardly into the carrier 20, as clearly illustrated in Figure 8. The outer end 36 of the spring rests in a radial slot in the housing t. Also secured in the end of the conductor strip 43 by means of solder or other suitable fastening means is one end'32 (Figure 4) of a flexible pigtail or stranded conductor 33. The other end of this conductor is secured, as by soldering,- to the terminal strip As illustrated in Figure 5, the cam 35 is prvided with a working face 36, a shoulder 40, and another working face 35 for purposes to be later described. Mounted on the lower face of the cover 4 on a pivot pin 31 is a latch 39which is held in the position shown in Figure by means of a spring 38 and a stop 38 secured on the cover.

The cylindrical carrier 20 is provided with a central hub 4| which projects into a hole in the base of thehousing 3 in alignment with the coil spring 3|. At the point of the connection between the hub 4| and the carrier 20 is an integral shoulder or collar 42 which rests on the top side of the bottom wall of the casing. It will be noted that the hub 4| has a loose fit in the passage in which it lies. At this 'point it will be noted that the head of screw 34, see Figure 8, projects into a central hole in the cover 2| of the movable member 20. This hole is large enough to likewise provide a loose fit for a purpose to be described later. A

Referring to Figure 18, it will be seen that the bottom wall of the casing 3 in the main chamber is cut away to form a groove which is partly circular and partly straight, as indicated at 44, which straight side gradually recedes from the center of the chamber. At 20' is a lug formed on the bottom of the carrier 20, see also Figure 9, which serves as a stop by engaging the end wall of the circular portion of the groove to limit the counter-clockwise or circuit opening movement of the carrier 20. A finger 45 projects into this groove for cooperation with the cam surface 44. This finger piece is an integral part of a lever 41, see Figures and 14, for example, and

5| which is positioned for sliding movement in the direction of its length along a chord 'of the cylindrical carrier, as is clear from Figure 10.

-This contact may slide through an opening 20" in the side wall of the carrier 20. A pivot pin .53 is secured on the other arm of the bellcr'ank lever 48 and mounted on it is a very small lever having a pair of projecting ears 54 and 55 which are connected by faces which meet at an acute angle, as is clear in Figure 11. Extending in an opposite direction from the pivot pin 53 is an car 56 positioned to engage an integral upstanding stop 51 on the adjacent portion of the bellcranir lever 41. A spring 58 engages the little lever on the pivot pin 53 to hold it against the stop, as shown in Figure 11. The bellcranir lever ii, the little lever pivoted on it, and the links 5% are preferably made of metal but need not necessarily be made of metal since they do not carry any current. A larger spring 52 is mounted on the pivot pin 48 and engages the linkage at the pivot point 49 and the inner wall or the carrier at. As will be seen from Figures 10 and ii, the lever 47, the links 59 and the contact iii form a toggle arrangement and the spring 52 tends move this toggle arrangement out of straight line position to the broken down position shown in Figure 10.

At this point it may be noted that the finger piece 21 is on a lever 27a pivotaliy mounted on the under-side of the cover it of the carrier. Also mounted on this lever so as to depend down into the carrier is a finger piece 21" which occupies various positions as indicated in the drawings.

At 59 is a right angle support which is secured in the carrier to the lead strip 43 by means of a screw 43. Secured to the support 59 is a bimetal arm 60 which is connected to the contact 5| by means of a flexible lead or pigtail $2. The lead is secured to the contact in any suitable way, as by soldering or the like, and is attached to the bimetal arm 6|] by means of a clip iii,

solder, rivets, and the like. As illustrated in Figure 19, the bimetal lever 60 is connected to the lead intermediate its ends. The free projecting scribed later.

. When the parts are in off position the operating handle or knob 3 is in the position shown in Figure l, which leaves the cam 35 and the latch 39 in the position shown in Figure 5. The carrier 20 is in the position shown in Figures 3 and 10, the latter of which shows the position of the parts within the cover. Figure 12 shows the position of the carrier.

In order to close the device the operator turns the knob l3 in a clockwise direction from the off position, as far as it will go, bringing its upper end in the region of the re-set position.-

nected linkages to move out to a straight line position as shown in Figure 11, projecting the contact 5| from its withdrawn position, Figure 10, to the position shown in Figure 11. The little lever on the pivot pin 53 has moved to the position shown in Figure 11 under the influence of spring 58. To do this the rear end of the ear 54 rubbed against the left hand face of the bi metal element 60, Figure 11, causing the little lever to pivot on the pivot pin 53 against the action of spring 58. Thus this part of the device is free of this structure so that the latch car 54 may move past the relatively rigid bimetal element 60 by swiveiling on its pivot pin 53 without practically any wear. The only force to be overcome is that of the light spring 58. Likewise during this motion the spring 3| in the bottom oiv the device is placed under stress so that as soon as the pressure is let up on the knob i3 or it is turned backwardly, that is, in a counter-clockwise direction, the carrier 20 will move back a short distance until the latch lever 24 engages in the notch 25 in the circular wall of the housing 3, see Figure 16. If the knob is released the parts stop in this position. At this time, as is clear from Figure 16, it will be seen that although the contact 5| is projected it does not engage the fixed contact i8. Thus the main circuit is not yet closed. This is the in-between position referred to before.

In order to put the device in on" position, the knob is is rotated to "on" position and as this is done the face of the cam 35 moves around to engage the adjacent end of the latch 24 and moves it out of the notch 25. This frees the 5 carrier so that under the influence of spring II it moves to the position shown in Figures 15 and 17, at which time contacts 5| and I8 engage to lock the carrier against any further movement. This movement of cam 35 causes the shoulder on it to pass the latch 39 so that any attempt to again rotate the knob in a clockwise direction will be prevented. This involves the so-called,

free tripping of the device, that is to say, that once it moves to closed circuit position it is out of the control of the operator to the extent that he could not hold it in that position. Thus, if the circuit is closed onan overload it cannot be held on it and is free to immediately open the circuit, The latch 39 cooperates with the side of the carrier 25, which is a little higher thanthe plane of the top of the carrier, as is clear from Figure 8 and which portion includes the shoulder 28. Thus when the switch goes to "01! position the latch 39 is moved out of the way so that the cam 35 may pass it during motion of the device to re-set position. y

In the on position, the parts as stated above are as illustrated in Figures 15 and 17. The toggle linkage which includes the contact ll is in a 2,261,139 position of the parts on the cover aswell as the.

straight line and is held against being collapsed by the spring 52' because the car 54 of the little lever is bearing against the bimetal element 55 and the car 55 engages the stop 51 so that this condition cannot be disturbed. With the device in on" position, current flows from the circuit through contact l8, contact 5|, flexible connection 52, that portion of the bimetal element 54 between the clip 6| and the support 59 through the support to the center lead 43 through the flexible connection 3| on the bottom of the device to the other circuit wire.

When an overload develops in the device the bimetal element is so constructed that it curves outwardly, that is, its free end moves toward the right, Figure 15, until it disengages the eat 54. When this happens spring 52' will force the toggle linkage out of alignment so that it collapses, withdrawing the contact 5| into the carrier. The result is that the locking engagement of that contact with the fixed contact II is destroyed and the relatively heavy coil spring 3| causes the carrier to snap to the off position, Figure 10. At this point it may be noted that the acute angle formed between the ears 54 and 55 on the little lever is provided so that the device may be accurately calibrated in order that the end of the bimetal element will engage the ear 54 always at the same place and not at the corner of the angle where dirt, burrs, and other material might collect to interfere with the accuracy of operation.

At this point it might be well to also note that the blmetal element is made as illustrated in Figure 19 so that only a portion of it is included in the circuit, thereby reducingthe resistance of this portion of the circuit and keeping the load imposed by the device, which is a loss load," small. The end of the bimetal element is of reduced section so that it will heat by conduction to the same temperature as the rest of the element so that the whole element will perform its function.

Another advantage of this arrangement is that it removes the connection from the region of the point of engagement between the bimetal element and the latching ear 54, thereby simplifying the structure. Likewise, it may be noted that the carrier is relatively free in its supports at the hub 4| and the screw 34 so that it can be moved around under the stresses on the device at closed circuit position so that the contacts 5| and I8 may properly align to ensure locking and a maximum area of contact therebetween. The construction provides what may be termed a floating contact carrier or member because of its freedom of motion to permit proper alignment of the contacts. Since the end faces of contacts 5| and II are plane and it is across these faces that the current flows, it is naturally desirable that the maximum area of contact result. The spring II exerts a fairly large force on the device and'by leaving the carrier free in the manner explained the contacts can properly engage. The collar or shoulder 42, Figure 8, ensures that there will not be any undue tipping ofthe carrier while allowing this alignment of the parts.

When the device springs to open circuit condition any are that may be drawn between the contacts 5| and I8 is drawn, Figure 17, in a counterclockwise direction down into the narrow confines of the arcuate chamber between the wall of the housing and the wall of the carrier. At the same time the gases generated rapidly build up the pressure in' this restricted chamber so that the are is rapidly extinguished. This pressure is relieved through passage 29 into chamber 80, see Figure 6, and finally escapes through the port 80'. By the time it reaches the atmosphere it has sufficiently. expanded and cooled so that it is no longer a, source of fire or injury hazard.

When the device is in on" position as shown in Figure 17 it maybe manually put in "off" position by turning the knob I3 from its up and down position to its of! position. As this movement occurs, the face 35", Figure 12, of cam 35 engages the finger 21, causing it to rotate in a counter clockwise direction. This moves the finger 21', Figure 17, into engagement with the free end 60' of the bimetal element and then springs it out of engagement with the ear 54. This, of course, frees the toggle so that the spring 52' may collapse it and the device springs ta "oflP position.

The carrier is stopped in its opening movement at about the time spring 8| has expended its force by engagement of the lug 20' on the bottom of the carrier 20 with the end of the arcuate groove in the bottom of the casing 3, see Figure 18. The device is then ready for a new cycle of operations to close the circuit to which it is connected.

For emphasis it may be noted that the plane of engagement between the faces of the contacts 5| and I8 is oifset or at an angle to a tangent to the carrier in the region of the contact so that there is a sort of wedging action resulting from the attempt of the contact 5| to move past the contact I8 as long as contact 5| is held in projected position. This ensures a'positive lock and thereby eliminates separate locking mechanism for holding the carrier in circuit closed position. The contact 5| moves through an opening in the side wall of the carrier 20 so as to engage the sides of the opening at its sides and thereby allow it only a straight line or longitudinal movement. In other words, the slot 20", see Figure 10, in which an ear of the cover 2| lies, connects with a lower slot 20a in which the contact 5| has a sliding fit.

The double-pole switch of Figures 20-26, in-

elusive, will now be described in detail. In starting, it may be noted that Figures 21, 22, 23 and 25 are full size. As before, the device is shown with an insulating base I0, shaped similar to that of I the single-pole switch. Mounted on this base is a rectangular housing II having a removable cover I2 and an operating knob I3 as before. In this case the base is provided with four terminal strips M, I5, I6 and IT in view of the fact that it is a double-pole structure. These terminal strips are provided with binding screws for attachment of the circuitwires in accordance with the usual practice. As is clear from Figure 23, the terminal strip 'II extends up into the housing and has mounted thereon the fixed contact 18 which projects through an opening in the. horn fibre strip I9 which protects the housing against carhonizing. In a'similar way the terminal strip 14 extends up into the housing and is provided with the other fixed contact 80 extending through which is provided, as in the case of the single-' pole switch, with a removable cover 85'. At 86 is an angled lever pivotally mounted ona pivot pin 81 secured to the cover and arranged so that when the switch is in re-set" position the heel of that lever will engage the shoulder 84 and hold the member 85 in that position until released for movement to "on position as before.

A spring 88 bears on the lever 88 to urge it to a position to engage the shoulder 84 as the rotor moves from the position shown in Figure 1 in a clockwise direction to re-set positionithat is. the position corresponding to that of the singlepole switch in Figure 11). Pivotally mounted on the cover 85' on the pivot 89 is a U-shaped lever 90, in the slot of which engages a pin 92 coming up through a slot in the cover 85', as is clear from Figures 21 and 26.- A spring 9| engages a shoulder on the cover 85' and a projection on the lever 90 so as to hold it in the position shown in Figure 21. Mounted on the cover 12 is a short shaft 93, to the outer end of which is secured the operating knob I3. The inner end of the short shaft 93 has straight sides, as is clear from Figure- 21, on which is locked a cam 94 which is held thereon by means of a round head screw 95. As shown in Figure 26, this screw fits loosely into a central opening 85" in the cover 85 of the oscillatable contact carrier 85.

At this point it'may be noted that the U-shaped lever 90 has its longer end curved upwardly, as indicated in Figure 26, to engage a working surface on the cam 94, as will be explained later. The cam 94 is provided with an ear as shown positioned to engage an upstanding shoulder 94' on the cover 85 and by means of which the carrier 85 may be rotated in a clockwise direction by the knob I3 to move it to re-set position. As shown in Figure 24, the cavity in the main housing II, in which the oscillatable carrier 85 2 moves, has two arcuate walls II closely spaced to the carrier to form restricted arcuate chambers into which the arcs are drawn when the switch breaks the circuit. At the end of each oi these restricted passages are passages 90 and 98, respectively, going down through the housing and opening into expansion chambers 91 and 99, respectively, as is clear from Figure 23. As in the case of the single-pole switch, the expansion chambers open to the atmosphere through holes in the base I0 positioned at the opposite ends of the chambers from the passages 95 and 98.

As is clear from Figure 26, the carrier 85 is provided with a central depending hub I00 01' insulating material, as is the carrier 85 and its cover 85'. It will be seen from this figure that the hub .I00 forms a loose fit in the circular passage IOI in the housing through which it passes. The carrier 85 is provided with a reentrant central portion extending in an axial direction with respect to the hub I00, on which is secured, by means of a screw I08, a double-ended lever I 02, the shape of which clearly appears in Figure 24. The lower terminal end of the hub I00 is cut away on a diameter to provide two levers, as is clear from Figure 26. Extending down through this hub are the metal strips I04 and I08, which are secured in place by screws, as shown. The lower ends of these strips are respectively connected to the pigtail or fiexible connectors I05 and I01 by means of solder, riveting, and the like. The other end of the pigtail I05 is connected to the. terminal strip 18, as is clear from Figure 23, and the other end of pi tail I01 is connected to the terminal strip 15. Interposed between these pigtails is the disc I09 of any suitable insulating material. A spiral spring I08 surrounds the central hub I and has one end locked in the hub, as is shown in Figure 25, and the other end in a slot in the adjacent part 0! the housing II.

The upper end of the conducting strip I04 is secured in any suitable manner to a bimetal element H0 and likewise secured to the upper end of the conducting strip I08 is another bimetal element III. As shown in Figure 24, these bimetal elements extend horizontally and parallel to each other. When the switch is in closed position, as shown in Figure 24, the free end of the bimetal element I I0 engages an upstanding pin I02 secured on one arm 01' the double-ended lever I02. Similarly, the free end of bimetal element II I engages the upstanding pin 92, secured on the other end of the double-ended lever I02. Pivotally mounted on a pivot pin H2 in the bottom of the cavity of the carrier 85 is a bellcrank lever H8, one arm of which has an upstanding projection II4 which fits in a notch in the adjacent end of the lever I02, see Figure 24. The other arms of the bellcrank lever II 3 is pivotally connected at II5 to a pair of links II6, which in turn are pivotally connected to the contact II1 which cooperates with the fixed contact 80. The pair of links II6 engage the contact II I on both sides in a manner similar to the construction of the single-pole switch. A pigtail or flexible connection H8 is attached to the bimetal element III and directly to the contact II'I. pin II2, engages at one end with the inner wall of the carrier 85 and at the other end with the toggle linkage adjacent the pivot pin M5.

The construction of the other half of the device is similar. Pivotally mounted on a pivot pin I2I secured in the carrier 85 is a bellcrank lever I 22 which has an upstanding projection I23 engaging in a notch in the other end of lever I02 when the switch is closed. The other arm of the bellcrank is pivotally connected at I24 with a pair of links I25 which pivotally connect with the contact I26 which cooperates with the fixed contact I8. A pigtail I29 connects the bimetal element I I0 directly with the contact I26. A spring acts on this toggle arrangement in the same manner as does the spring I I9 act on its toggle arrangement. Bellcrank II 3 is provided with a downwardly extending projection I20 which passes through a slot in the bottom wall of the carrier85, as is clear from Figure 26. Similarly, the bellcrank I22 has a downwardly extending projection I21.

The bottom wall of the chamber in the housing II in which the carrier 85 oscillates is provided, as shown in Figure 25, with grooves shaped to provide camming surfaces I20 and I21 .with

A spring H0, mounted on the pivot knob I8 causes the movable carrier 85 to rotate with it through the co-action between the cam 94 and the shoulder 94', Figure 21, as previously explained. As the carrier reaches "re-set" position, the heel of lever 86 engages shoulder 84 to hold the carrier there. At this time spring I 08 is under tension and the contacts III and I26 have been projected by reason of the fact that the bellcrank levers have been rotated on their pivot pins through the engagement of the fingers I21 and I20 with the cam surfaces in i the bottom of the housing. The carrier now stays in this re-set position even if the knob I3 is released. At this time the contacts III and I26 do not engage their respective fixed contacts 8| and I8. Thus the circuit is still open.

To close the circuit, the knob I3 is moved back to on position (a ball detent, as before, in the knob engaging a depression in the cover 12). As the knob is moved back to "on position the cam is shaped to engage the adjacent end of lever 86, causing its heel to disengage the shoulder 84. Thus the carrier, under the influence of spring I08 as in the case of the single-pole switch, moves in a counter-clockwise direction so that v the projected contacts III and I26 engage their which the downwardly extending fingers I20 and I21 cooperate so that as the member 85 rotates in a clockwise direction to re-set position these fingers engage the camming surfaces and move the bellcrank levers about the pivot pins to straighten out the toggles so as to project the contacts II! and I26. Projecting downwardly from the carrier 85 are integral projections 85a and 85b which engage the ends of the recesses in the bottom wall of the housing II, as shown in Figure 25, to limit the oscillation of the carrier 85 in its open circuit movement.

The operation "of this switch is quite similar to the operation of the single-pole switch.- The knob I8 is rotated from the "01! position, Figure 20, to the "re-set position as the first operation. in closing the switch. This movement of the respective fixed contacts. The enga ging faces are at angles to the circular path of movement of the carrier and, therefore, a wedging action results to lock the carrier in closed circuit position. This position is maintained because the toggle mechanism of which contacts Ill and I26 are a part are extended and cannot collapse because the upstanding projections Ill and I23 engage the double-ended lever I22 as shown in Figure 24.

The circuit is as follows, starting for example from terminal strip I4. The current fiows through this strip to contact 80, through contact II'I, flexible connection H8, bimetal strip III, conducting strip I06, pigtail I01, to terminal strip 75. The current continues on through the load back to terminal strip 11, contact I8, contact I26, flexible connection I29, bimetal element II 0, conducting strip I04, pigtail I05, to terminal strip I6 If an over-load develops in the circuit, either one or both of the bimetal elements H0 and III will be distorted so that their free ends move outwardly, and through engagement with the pins 92 and I 02 cause the double-ended lever I02 to rotate in a clockwise direction, see Figure 24. When this movement has gone far enough to disengage lever I02 with the upstanding projections H4 and I23, the bellcrank levers H3 and I22 are free and their associated springs cause them to colapse, withdrawing the contacts III and I26 into the carrier 85. This breaks the locking engagement between those contacts and the associated fixed contacts whereupon spring I08 snaps the carrier in counter-clockwise direction, Figure 2a, to instantly open the circuit.

The switchrnay be moved from on pOsitiOn to "02! position manually by rotating the handle I3 to oil position. This carries with it the cam 94 which engages the bent-up end of the U- shaped lever 80, see Figure 26, to cause it to move the pin 82 extending upwardly from the lever I02 so as to move that lever in the same direction as with the bimetal elements it overheated and thereby release the toggles for collapse. The pin 92 extends to a sufllcient height so as to project through the cover 85 of the carrier 85 while the pin I02 is shorter.

For sake oi emphasis, it is mentioned separately that as indicated in Figure 26 the carrier 35 oscillates on freely fitting supports so that when the switch goes into on position the carrier may adjust its position to ensure that the contacts III and I 26 will have face to face engagement with the contacts 30 and I8, respectively, to give a maximum area of contact and minimum contact resistance.

In Figures 27 to 31, inclusive, is shown the final form of the structure, which in this case is of the single-pole type. to the ordinary safety fuse plug and is little larger than it, being shown in Figures 27 to. 30 in full size position. The main housing I30 in this case is cylindrical and is provided with a removable cover I3I, above which is the operating knob I33. Projecting from the lower end This device is shaped similar of the casing I 30 is the screw plug I32 by means of which the device may be mounted in the wellknown type of fuse block. The central contact I34, as in the case of a fuse, is one terminal of the circuit breaker while the threaded shell I3! is the other terminal. A conducting strip I35 extends from the shell I31 into the housing and on it is mounted the fixed contact I38. In the housing is the oscillatable carrier I36 of a construction just like that of the single-pole switch previously described in full detail. At I3! is the movable contact which projects through this carrier to engage the fixed contact when the switch is closed. The pigtail connects the contact I34 with the interior of the carrier as before and the spiral spring III) is connected thereto as before, The construction of this switch is otherwise like that of the single-pole type and its operation is exactly the same.

From the above description it will be apparent to those skilled in the art that the invention herein disclosed may be embodied in still other physical'structures without departure from the novel subject matter thereof. I do not, therefore, desire to be limited to the disclosure as given for purposes of illustration but rather to the scope of the claims granted me.

What I claim is:

1. In a circuit breaker, a closed housing forming a chamber, a fixed contact mounted in said chamber, an oscillatable carrier in said chamber, a contact on said carrier positionable to engage said fixed contact when the carrier is in closed circuit position, means for urging the carrier to open circuit position, said contacts when in engagement locking the carrier, in closed circuit position, and means for loosely confinin the carrier to an axis of oscillation whereby the carrier is moved by said means with respect to said axis to cause alignment of said contacts when they are engaged.

2. In a circuit breakena closed housing forming a chrrnber, a fixed contact mounted in'said chamber, an oscillatable carrier in said chamber, a contact on said carrier positionable to engage said fixed contact when the carrier is in closed circuit position, means for urging the carrier to 3. In a circuit breaker, a closed housing form ing a chamber, a fixed contact mounted in said chamber, an oscillatable carrier in said chamber, a contact on said carrier positionable to engage said fixed contact when the carrier is in closed circuit position, means for urging the carrier to open circuit position, said contacts when in engagement locking the carrier in closed circuit position, means for loosely confining the carrier to an axis of oscillation whereby the carrier is moved by said means with respect to said axis to cause alignment of said contacts when they are engaged, and heat responsive means on said carrier connected in circuit with said contacts when closed to move the contact on the carrier to destroy its locking engagement with the fixed contact upon overload.

4. In a circuit breaker, a closed housing forming a chamber, a fixed contact mounted in said chamber, an oscillatable carrier in said chamber, a contact on said: carrier positionable to enage said fixed contact when the carrier is in closed circuit position, means for urging the carrier to open circuit position, said contacts when in engagement locking the carrier in closed cir-. cuit position, means in said housing and on said carrier freely cooperating to provide a relatively fixed axis of oscillation for said carrier whereby the carrier is moved by said means with respect to said axis to cause alignment of said contacts when they are engaged, and heat responsive means on said carrier connected in circuit with said contacts when closed to move the contact on the carrier to destroy its lockingengagement with thefixed contact upon overload.

5. In a circuit breaker, a closed housing forming a chamber, a fixed contact mounted in said chamber, an oscillatable carrier in said chamber, a contact on said carrier positionable to engage said fixed contact when the carrier is in closed circuit position, means for urging the carrier to open circuit position, manual means for moving said carrier so that the contact thereon has moved past said fixed contact, and means on said carrier for holding it in that position, said manual means on initial reverse movement releasing said holding means whereby the carrier moves back to cause locking engagement between said contacts.

6. In a circuit breaker, a closed housing forming a chamber, a fixed contact mounted in said chamber, an oscillatable carrier in said chamber, a contact on said carrier positionable to engage said fixedcontact when the carrier is in closed circuit position, means for urging the carrier to open circuit position, manual means for moving said carrier so that the contact thereon has moved past said fixed contact, means on said carrier for holding it in that position, said manual means on initial reverse movement releasing said holding means whereby the carrier moves back to cause locking engagement between said contacts, and heat responsive means for destroying the locking engagement between said contacts upon overload.

7.'In a circuit breaker, a fixed contact, an oscillatable member having a contact thereon.

said member being positionable to engage said contacts,.means acting on said member always tending to move it to contact disengaging positIon. a manually operated actuator engageable with said can'ier to move it beyond circuit closed position against the resistance or said means, and means for holding the carrier in that position, said manual actuatorupon initial reverse movement releasing said holding means whereby said carrier moves in the reverse direction to cause the contact thereon to engage the fixed contact and hold the carrier in that position.

8. In a circuit breaker, a fixed contact, an oscillatable member having a contact thereon, said member being positionable to engage said contacts, means acting on said member always tending to move it to contact disengaging position, a manually operated actuator 'engageable with said carrier to move it beyond circuit closed position against the resistance of said means, means for holding the carrier in that position, said manual actuator upon initial reverse movement releasing said holding means whereby said carrier moves in the reverse direction to cause the contact thereon to engage the fixed contact and hold the carrier in that position, and heat responsive means in circuit with said contacts for moving the contact on the carrier with respect to the fixed contact upon an overload whereby said means snaps said carrier back to initial position.

9. In a circuit breaker, a housing forming a chamber, a fixed contact mounted in said chamber, an oscillatable hollow carrier in said chamber, a contact slidably mounted in said carrier, i

said contact being positioned substantially within said member in the open circuit position of the member, means in said member for causing the contact thereon to project from the member in closed circuit position, means for urging said member to open circuit position, and a manual actuator for moving said member to closedv circuit position whereby the contact on the member is projected to eng ge the fixed contact and hold the member in circuit closed position.

10. In a circuit breaker, a housing forming a chamber, a fixed contact mounted in said chamber, an oscillatable hollow carrier in said chamber, a contact slidably mounted in said carrier, said contact being positioned substantially within said member in the open circuit position of the member, means in said member for causing the contact thereon to project from the member in closed circuit position, means for urging said member to open circuit position, a manual actuator for moving said member to closed circuit position whereby the contact on the member is projected to engage the fixed contact and hold the member in circuit closed position, and heat responsive means in said member for causing withdrawing movement of the contact on the member to release it for open circuit movement.

11. In a circuit breaker of the type described, the combination including ahousing having a fixed contact thereon, an oscillatable carrier in sition, means for moving the carrier to closed circuit position and for projecting the contact therein so as to engage the fixed contact and hold the carrier in closed circuit position, and heat responsive means in circuit with said contacts for moving the contact on the carrier back thereinto upon overload to release the carrier for movement to open circuit position.

13. In a double-pole circuit breaker, the combination including a housing having a. pair of fixed contacts therein, an oscillatable carrier in said housing, means for urging said carrier to open-circuit position, a pair of contacts on said carrier, and means for moving the carrier to closed circuit position and moving the contacts on the carrier toa position to engage the fixed contacts respectively to lock the carrier in closed circuit position.

14. In a double-pole circuit breaker, the combination including a housing having a pair of fixed contacts therein, an oscillatable carrier in said housing, means for urging said carrier to open circuit position, a pair of contacts on said carrier, means for moving the carrier to closed circuit position and moving the contacts on the carrier to a position to engage the fixed contacts respectively to lock the carrier in closed circuit position, and heat responsive means in circuit with each pair of contacts for moving the carrier contacts from locking engagement with the fixed contacts upon an overload.

15. In a double-pole circuit breaker, the combination including a housing having a pair of fixed contacts therein, an oscillatable carrier in said housing, means for urging said carrier to open circuit position, a pair 01 contacts movably mounted on said carrier, means for moving said carrier to circuit closed position and moving said contacts with respect to the carrier to cause their engagement with the fixed contacts respectively, means on said carrier for holding the contacts thereon in said positions, and heat responsive means in circuit with said contacts to move said last means to release said contacts upon the development of an overload, the cooperation between the contacts in pairs holding the carrier in closed circuit position.

16. In a double-pole circuit breaker, the combination including a housing having a pair of said housing having a contact therein, spring means for urging the carrier to open circuit position, and means for moving the carrier to closed circuit position and for projecting the contact therein so as to engage the fixed contact and hold the carrier in closed circuit position.

12. In a circuit breaker of the type described, the combination including a housing having a fixed contact thereon, an oscillatable carrier in said housing having a contact therein, spring means for urging the carrier to open circuit pofixed contacts therein, an oscillatable carrier in said housing, means for urging said carrier to open circuit. position, a pair of contacts movably mounted on said carrier, means for moving said carrier to circuit closed position and moving said contacts with respect to the carrier to cause their engagement with the fixed contacts respectively, means on said carrier for holding the contacts thereon in said positions, heat responsive means in circuit with said contacts to move said last means to release said contacts upon the develop,- ment of an overload, the cooperation between the contacts in pairs holding the carrier in closed circuit position, and manual means for moving said holding means to destroy the locking engagement between said contacts when desired.

JAMES H. BURNSIDE, 2ND. 

